It’s tradition in the western world to associate aspects of the human personality with good or evil. Whether you regard the good and evil at play here as the result of external forces or as an inherent part of the human psyche is irrelevant, what matters is that some forms of behaviour are regarded as good and some evil, or at least bad.
In most cases the majority of right-thinking individuals would agree what is good/bad, virtuous/evil. Murder, theft etc are obvious candidates for the evil tag and kindness, compassion and the like as traits that would be thought of as good and desirable.
The aspect of human behaviour that is too often associated with the darker side of the human condition is sex and sexuality. The reasons have their roots in the need for the ruling classes to find new ways to control those serving them. In some ancient societies sex and sexuality were celebrated and a source of joy and yet in each case subsequent regimes and philosophies have marked their predecessors as depraved and degenerate.
One of the most recent examples of this was the advent of national socialism in Germany in the 1930s. The previous Weimar Republic was denounced as corrupt and decadent (morally and sexually) by the Nazis who attributed it with the economic woes of the German nation after the first world war. Yet what followed was what is generally regarded as one of the most inhuman and vile regimes ever to take power in Europe.
Looking further back and perhaps with more relevance directly to sexuality the civilisations of Egypt, Rome and Babylon have all been depicted as evil, at least in part because they embraced sex and the joy which can be derived from sex. Yes these societies all had reprehensible aspects, especially when viewed through our modern eyes, but despite many centuries criticisms made of them by civilisations that succeeded them still colour our views of sexuality.
In Egypt at one point the Pharaoh would masturbate every morning symbolically re-creating the universe as his supposed god-ancestor had done. In Rome pagan festivals celebrated fertility and procreation, Lupercalia being the most well know which has been watered down over two millennia and adopted as Valentine’s Day.
Anal sex too has been condemned as an intrinsically evil act because of its association with the residents of a certain town next to the Dead Sea.
In every case it seems that there is no logical reason to condemn a sexual practice (so long as the partners consent and are not blood relatives) except to use that condemnation as part of a propaganda campaign against a former enemy or regime.
Sodom may have been a pretty nasty place when Lot saw it, but buggery was probably the least of its problems. More likely it was a lawless and cruel society like many in the world at that time. The anal sex just got co-opted as a shorthand for deviance and lack of morals.
Egypt was cruel and oppressive to many of those who lived there, and the ruling classes did interbreed. In fact that may have contributed to their downfall. However cracking one off is not evil in itself.
And as for you people running around the streets of Rome getting excited and spreading their wild oats … that didn’t bring down the empire, the impossibility of managing the largest civilisation in the world for 600 years did that.
If you want to think of us all as inhabited by angels and daemons then fine. However those little putti wearing halos or horns are not evil just part of a mixture of what makes us human.